Medicine of the Ageing, Catholic University, Rome, Italy.
Neuropsychologia. 2012 Jul;50(8):1980-9. doi: 10.1016/j.neuropsychologia.2012.04.023. Epub 2012 May 7.
An impairment for verbs has been described in patients with Parkinson's disease (PD), suggesting that a disruption of frontal-subcortical circuits may result in dysfunction of the neural systems involved in action-verb processing. A previous study suggested that deep brain stimulation (DBS) of the subthalamic nucleus (STN) during verb generation may affect the ability to select from many competing lexical alternatives. In this study, 12 PD patients who had undergone bilateral STN DBS and completed an 8-year follow-up and 14 matched normal controls were administered action and object naming tasks and verb and noun reading tasks. Their responses were recorded using a microphone, resulting in a signal that marked the onset of the verbal response and allowed to measure response times (RTs). Accuracy was scored manually.
Overall performance in naming (independently of stimulation): In naming task controls were faster and more accurate than PD patients. In both groups, performance (accuracy and RTs) was worse on action naming than object naming. PD patients were significantly slower than controls in naming actions. Effect of stimulation: Compared with the OFF stimulation condition, in ON stimulation condition PD patients showed improved performance on object and action naming tasks (increased accuracy, faster RTs), with a decreased number of semantic errors. Some evidence also emerged that action naming in the ON stimulation condition improved more than object naming. On noun and verb reading tasks, although accuracy was at ceiling in both groups and no significant difference was observed in RTs for nouns and verbs, PD patients were slower than controls.
Our findings suggest that STN DBS may improve lexical search in PD patients. We hypothesize that STN stimulation may facilitate the motor components involved in naming and reading tasks (increased speed of speech onset), resulting in shorter RTs in both naming and reading and, to some extent, in increased accuracy in naming due to fewer omissions (no response within the 7500 ms time limit). However, to account for greater accuracy in naming due to decreased number of semantic errors in the ON stimulation condition, we hypothesize that STN stimulation restores the activity of the corticostriatal circuits involved in selection processes of a target word among different alternatives.
描述帕金森病（PD）患者的动词障碍，提示额皮质下回路的破坏可能导致与动作动词处理相关的神经网络功能障碍。先前的研究表明，在动词生成过程中对丘脑底核（STN）进行深部脑刺激（DBS）可能会影响从许多竞争词汇中选择的能力。在这项研究中，12 名接受双侧 STN-DBS 并完成 8 年随访的 PD 患者和 14 名匹配的正常对照者进行了动作和物体命名任务以及动词和名词阅读任务。他们的反应通过麦克风记录，产生标记言语反应开始的信号，并允许测量反应时间（RT）。准确性由手动评分。
命名的总体表现（独立于刺激）：在命名任务中，对照组比 PD 患者更快、更准确。在两组中，动作命名的表现（准确性和 RT）均比物体命名差。PD 患者的动作命名速度明显慢于对照组。刺激的影响：与 OFF 刺激条件相比，在 ON 刺激条件下，PD 患者在物体和动作命名任务中的表现有所改善（准确性提高，RT 更快），语义错误的数量减少。也有一些证据表明，在 ON 刺激条件下，动作命名的改善程度大于物体命名。在名词和动词阅读任务中，虽然两组的准确性都达到了上限，名词和动词的 RT 没有观察到显著差异，但 PD 患者的反应速度比对照组慢。
我们的研究结果表明，STN-DBS 可能改善 PD 患者的词汇搜索。我们假设 STN 刺激可能有助于与命名和阅读任务相关的运动成分（言语起始速度加快），从而导致命名和阅读的 RT 更短，并且在一定程度上由于省略较少（在 7500ms 的时间限制内没有反应），命名的准确性提高。然而，为了解释在 ON 刺激条件下由于语义错误数量减少而导致的命名准确性更高，我们假设 STN 刺激恢复了与目标词在不同替代词中选择相关的皮质纹状体回路的活动。
